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In The Cable Car in America, George W. Hilton identified four essential features of cable car technology:
In this page, I will also describe some other features of cable cars that are not distinct or essential to the technology, but which I find interesting. Use your browser's "Back" button to return.
Types of Grips (front view)
The grip can be in three positions:
Grips were the source of constant patent litigation during the period when cable cars were widespread.
Hallidie and Eppelsheimer's original grip was a bottom grip. With a bottom grip, the cable is picked up and dropped through the bottom of the grip. It is easiest to pick up and drop the cable with a bottom grip. The surviving San Francisco cable car lines use a later bottom grip designed by Eppelsheimer.
The side grip, single jaw or double jaw, was the most popular type of grip during the period when cable car lines were being built. Designers considered side grips to be simpler, and to have less danger of the cable being accidentally torn out of the grip on a steep grade. Conversly, it was harder to drop the cable at a crossing or in an emergency with a side grip. Double jaw side grips had jaws on each side. This was considered useful for complicated duplicate cable systems like the ones in New York City, and for light single-track systems, as in the Second Street Cable Railway in Los Angeles.
Top grips were used by companies that did not want to pay royalties to grip patent-holders, such as the North Chicago Street Railroad. They required deeper conduits than bottom or side grips. They made it almost impossible to drop the cable for a crossing or in an emergency. There were no redeeming qualities.
Hallidie's original grip used a horizonal wheel to open and close the jaws. The majority of cable car lines used levers to operate their grips, because a long lever gives good leverage. Levers, however, took up space in the car that could be used for fare-paying passengers. Some lines used vertical wheels mounted on the front platforms of cars. This used less space. The surviving San Francisco lines use levers.
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The cable is an endless wire rope, made of a hemp core wrapped with strands made of groups of small steel wires. The hemp core gives flexibility and the steel strands give strength.
In cable-making terminology, the direction in which the strands are wrapped around the core is called the lay. In a standard lay cable, the strands are wrapped around the core in the opposite direction from that in which the wires are wrapped within each strand. In a standard lay cable, the wires which peak near the surface of the cable tend to fracture and break, which can lead to broken strands, which can jam in the grip and cause a car to run away. In a Lang lay cable, the type currently used in San Francisco, the strands are wrapped around the core in the same direction as that in which the wires are wrapped within each strand. Lang lay cables are less susceptible to broken strands.
Cables were treated with a variety of substances to make starts smoother. San Francisco used pine tar until the system was rebuilt in the 1980's. Now Muni uses a synthetic lubricant. Operators claim that it makes the cable too slippery.
Crossing two cable car lines is a complicated operation. One line's cable has to pass below the other line's. The method of determining which line was able to hold the cable (the superior position) and which had to drop it (the inferior position) and coast across varied from city to city. At all the crossings in San Francisco, superiority was determined by seniority. The first crossing between two lines was at Larkin ( Sutter Street Railway) and Geary (Geary Street Park and Ocean Railway) Streets. The Larkin Street line had the superior position because it was there first. Some cities, such as Kansas City, considered safety in determining superiority.
At the only surviving cable railway crossing, at California ( California Street Cable Railway) and Powell (Ferries and Cliff House Railway) Streets in San Francisco, the California Street line has superiority because it was built in 1878, while the Powell Street line was built in 1886. Because of the dangerous position, with California Street rising to and from the intersection and Powell Street rising in both directions to the intersection, this crossing is controlled by a signal tower. Read Emiliano J Echeverria's article about the tower.
The last cable car line built in San Francisco, the California Street Cable Railway's O'Farrel/Jones/Hyde line had to drop rope 22 times (9 crossings, powerhouse, end of line) on a round trip. This is described in Gelett Burgess' poem "The Ballad of the Hyde Street Grip".
San Francisco's current system uses four cables, each run at 9.5 miles per hour:
San Francisco currently uses a cable with a diameter of 1.125 inches (thanks to Manny Manasievici for the measurement).
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The trackbed of a cable car line, including the rails and the conduit, is much more complicated than a standard railway trackbed. The rails cannot be supported by cross-ties because a way has to be left open for the slot. Most lines used a metal form called a yoke to support the rails and form the conduit.
Within the conduit, a variety of sheaves and pulleys are used to support the cable. On straight, level track, when the cable is not held in the grip of a passing cable car, the cable runs on a series of vertical carrying pulleys. At each terminus, the cable reverses direction on a large horizontal terminal sheave. At the top of a hill, a heavy crown pulley resists downward pressure. At the bottom of a hill, a depression pulley, usually movable on a bottom grip line, keeps the cable from rising out of the slot.
The first cable car lines, like the Clay Street Hill Railroad, ran in a straight line from terminal to terminal. The only track curves were used to bring cars into and out of the car barn.
The first cable car line to include a curve in its revenue trackage was the Presidio & Ferries Railway, which had to move cars at an oblique angle from Columbus to Union Street. The shallow angle and local geography allowed cars to drop the cable and coast around the corner. This was referred to as a "let go" curve. The Hallidie bottom grip allowed the cars to drop the cable and to pick it up around the corner with ease. A large horizontal sheave allows the cable to change angle from one street to another. Large sheaves are good because they put very little stress on the cable.
Other locations did not allow for the use of a let go curve. In some cases, the curve was too sharp; in other, the curve had a hill climbing towards it in one or both directions. This called for the invention of the "pull curve", which allowed a car to traverse a curve while holding onto the cable. George S Duncan built the first pull curve in Dunedin, New Zealand, for the Roslyn Tramway, which had to carry cars over a climbing curve around Saint Joseph's Cathedral.
The pull curve is complicated because it needs a series of small horizontal sheaves placed close together to keep the cable in position under the slot around the curve. As the car passes through the curve, it pulls the cable up and away from the sheaves. This puts a heavy lateral strain on the thin grip shank; the lateral forces tend to try to pull the cable out of the grip, or to pull the grip over to strike the sheaves. Pull curves generally include a "chafing bar"; the grip slides along the bar, which holds the grip away from the sheaves. In general, calls have to go around a pull curve with the cable tightly held, at full speed. This can be dangerous in heavy traffic, especially at locations like Manhattan's famous Dead Man's Curve.
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During the cable car era, powerhouses were generally steam-driven, so they required lots of room for boilers and coal storage. The surviving San Francisco cable lines have been driven by electricity since the 1920's.
Methods of driving the cable varied, but had to addresss certain problems. The cable had to be set in motion without slipping. This was commonly done by wrapping the cable one or more times around a large powered wheel called a driver, and usually one or more times around a small, unpowered wheel called an idler. The cable had to have a constant level of tension. This was dealt with in various ways. The most common method was the one still used in San Francisco, the tension run. After the cable leaves the driver, it runs down a long corridor to a smaller sheave, which is on a movable platform over a long pit. The platform can be moved along the corridor to keep the cable tight when it stretches. To deal with short-term changes in tension caused by cars gripping and ungripping the cable, the sheave can move on the platform, pulled tight by a weight that hangs in the pit.
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Turning the Cars
Unless a transit line operates on a loop, like the Tacoma, WA line, its vehicles have to change directions when they reach the ends of the line. The way in which a vehicle changes directions is in part determined by whether the vehicle is single or double-ended. Single-ended cars or trains were most common during the cable railway era, but San Francisco's surviving lines use both types.
Single-ended Powell Street cars use turntables to reverse direction. I took the following series of photos around the Powell and Market turntable in December, 2001.
When the car is off of the turntable, the gripman will jump on and pull the track brake handle to stop the car over a small depression, which puts the grip in position to pick up the cable. When he pulls the grip lever part way back, the car is in partial release.
The Powell Street turntable was replaced in October-November, 2002.
California Street cars are double-ended. They change directions using a simple cross-over. I took these two photos in January, 2002 at California and Drumm.
At Van Ness, the California Street line ends on a grade. Outbound cars run straight up to the terminal. They drop the rope and coast back down through a crossover to the inbound track.
Lines in some cities used loops to turn single-ended cars. No San Francisco cable car line used a balloon loop like one at the Camden Ferry in Philadelphia, but for a time both the Sacramento/Clay and Washington/Jackson lines ended in loops.
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Hear a Cable Car Bell.
Bells were a common method of signalling within and outside cars throughout the horse, cable, and electric street railway periods.
Current San Francisco cable cars use a large bell operated by the gripman to warn pedestrians and other vehicles, and to communicate with the conductor. The conductor uses a smaller bell for internal communication with the gripman.
Joe Lacey, former cable car conductor, was kind enough to provide some information
about current and former bell signals:
According to the Market Street Railway, Motormen's, and
Conductors training manual of July 1929 ,
On the Cable Cars in my era , and I haven't found my training manual
yet, the bells were
The three and four bells were used when backing down a hill, if the car had
to stop, this was most often on the Cal line at 5 pm between Stockton and Powell,
when a auto stopped in front of the Cable Car on the hill. Then the conductor had
to try to move the autos from behind the Cable Car , and the Conductor had
control of the car backing down to Stockton Street and stopping with the grip in the
depression of the hill in case the gripman dropped the cable. The gripman often gave two
bells on the main bell indicating the front end was clear and he had a green
signal and wanting two bells from the conductor, the conductor was in charge
of the car , and responsible for keeping it on time. There was also a special
signal, if there was a rapid succession of bells on the interior bell , from
either the conductor or gripman it ment there was something of special
interest to look at, eg: girl in mini skirt, extra crazy person etc.
I have a Cable Car bell on my rear deck now, and it is rung when the 49ers
make a touchdown.
According to the Market Street Railway, Motormen's, and Conductors training manual of July 1929 ,
On the Cable Cars in my era , and I haven't found my training manual yet, the bells were
The three and four bells were used when backing down a hill, if the car had to stop, this was most often on the Cal line at 5 pm between Stockton and Powell, when a auto stopped in front of the Cable Car on the hill. Then the conductor had to try to move the autos from behind the Cable Car , and the Conductor had control of the car backing down to Stockton Street and stopping with the grip in the depression of the hill in case the gripman dropped the cable. The gripman often gave two bells on the main bell indicating the front end was clear and he had a green signal and wanting two bells from the conductor, the conductor was in charge of the car , and responsible for keeping it on time. There was also a special signal, if there was a rapid succession of bells on the interior bell , from either the conductor or gripman it ment there was something of special interest to look at, eg: girl in mini skirt, extra crazy person etc.
I have a Cable Car bell on my rear deck now, and it is rung when the 49ers make a touchdown.
Jeff Cleveland has determined that cable car bells are currently (1999) manufactured at Gilberto Godoy's United Brass Foundry in San Francisco's Bayview District.
There is an annual Cable Car Bell Ringing Contest held in Union Square, usually on the second Tuesday in July.
The San Francisco Giants had a cable car bell mounted behind the backstop at Candlestick Park. After any inning in which the Giants scored a run, a groundskeeper rang it once for each run. At Pac Bell Park, they installed an entire cable car, retired Powell Street number 4, in August, 2000. The car is numbered 44 to honor Hall of Famer Willie McCovey. One group of four general admission fans gets to sit in the car. One of those fans gets to ring the bell after each inning in which the Giants score a run. Pretty cool. See some photos of car 44.
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Brakes are a critical component of any vehicle. Cable cars use braking systems that were once common on many different types of transit vehicles, but have since become rare.
Current San Francisco cable cars have three braking systems:
The cable also serves as a brake, retarding the progress of a car going down a steep hill.
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The Electrical System
A question arose about the electrical system used in current cable cars.
Early cars generally had oil or kerosene lamps for lighting. Current cars use a 12 volt system powered by 6 volt batteries connected in series. Running lights are amber lights on each corner of the front end of a Powell Street car, with a center headlight, and red lights on each corner of the rear. The lights are not very strong.
The batteries are charged every night. Along the storage tracks in the carbarn are cords that can be pulled down from reels and plugged into the charger on each car. A full charge will usually be sufficient for the next full day and night of service, but sometimes the cars don't get a full charge, or the batteries lose their ability to hold a charge as they get older. If the batteries run down on the road, they are replaced by a shop crew in the wrecker, just as the grips are.
For a time, the batteries also powered a windshield wiper on the center front window. The wiper wasn't very effective, so crews would wipe the window with a pouch of Bull Durham tobacco. My grandfather did that on his auto. The wet pouch leaves a film of oil which causes rain to run off smoothly. Some people prefer to use old newspapers.
Thanks to Bob Murphy, Joe Lacey, and and jeff99 for providing information on this topic.
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